PROJECT SUMMARY The Center for Clinical Epidemiology and Biostatistics (CCEB) and the Abramson Cancer Center (ACC), an NCI-designated Comprehensive Cancer Center, in collaboration with the Division of Hematology-Oncology of the Department of Medicine and the Division of Oncology of the Department of Pediatrics, all at the University of Pennsylvania (Penn) Perelman School of Medicine (PSOM), propose to continue an innovative, rigorous, and successful two- to three-year training program for investigators in cancer clinical epidemiology. This training program attracts cancer clinical epidemiology trainees from across the country; its graduates are placed in institutions nationwide, resulting in a program of high impact.The program will: 1) train primarily physicians to be rigorous, independent academic investigators able to use a wide range of epidemiological methods to address clinical cancer research questions using a variety of designs; 2) provide closely mentored research experiences with faculty preceptors in clinical epidemiology, biostatistics, and cancer; and 3) strengthen the links between traditional epidemiology and cancer research. Didactic training is provided under auspices of the Master of Science in Clinical Epidemiology (MSCE) program which provides regular feedback to the directors of the training program (CCETP) to maximize the progress of each fellow. The training program is focused on the completion of a rigorous mentored research thesis project. The thesis is based on the long term research interests of the fellow, carefully designed in a grant proposal format, executed, analysed, and written up as first author manuscript(s). The principal concepts necessary for rigorous research are taught in courses of fundamental epidemiological methods, cancer and molecular epidemiology, and biostatistics, elective courses relevant to the trainees' methodologic interests; journal clubs and clinical research conferences conducted by participating faculty, the CCEB, ACC, and adult and pediatric oncology divisions; extensive independent readings; and instruction in the responsible conduct of research. Strengths of the proposed program are: 1) the long history of successful research training programs in the CCEB, ACC, and adult and pediatric oncology divisions, including this training program; 2) the collaborative links that have been forged among faculty with interests in clinical research in cancer; 3) the comprehensive course offerings and research programs that are available to trainees; and 4) an extensive set of experienced and multidisciplinary faculty with successful training records. In addition, numerous existing large databases that can be used for research projects and training; a broad array of specialized analytic capabilities available for clinical studies employing methods of clinical epidemiology (e.g., clinical trials, case-control, cohort research, etc.); and commitment of faculty to collaborative research and training, combine to provide an ideal environment for this training program. Finally, the PSOM promote an academic environment in which basic and clinical research are encouraged and viewed as attractive career paths for physicians.